Announcement

Collapse
No announcement yet.

Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

    A friend of mine brought me this PC to have a look at. It runs off a 19v adapter and the motherboard is very similar to a laptop board so I thought I'd post in here.


    The system does not POST or beep.
    The power LED stays orange.
    The fan runs at full speed.
    The power button won't turn it off again even if you hold it in.
    There is no display on screen...

    ...BUT if you plug something into the HDMI input port, it will display an external signal correctly as well as audio. Though that seems to be handled by a separate Realtek IC.


    The battery is OK (3.05v) and resetting CMOS does nothing.

    I have tested voltages and everything seems to be working, however there is no Vcore, likely because the VRM controller is not getting an enable or powerok signal.

    The BIOS flash has 3.3v but there is no activity on the data lines whatsoever.

    My first guess is that the SuperIO chip (ITE IT8732F-CXS) is bad.
    Is there anything else likely? I hope it is not some shorted ceramic or open resistor etc because I can find no datasheet for IT8732F, nor schematic for the motherboard (code 48.3KP01.011)
    Attached Files
    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
    -David VanHorn
    Tags: None
    #2
    Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

    I'm confused, how can you get signal on external display if there is no CPU VCore?
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

      #3
      Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

      Originally posted by piernov View Post
      I'm confused, how can you get signal on external display if there is no CPU VCore?
      Not on external display, from external source.
      You can use it like a monitor/TV when the PC is powered off.

      Here it is plugged into my PS3. Confusing, I know. There is no indication anywhere that the HDMI port is actually an input. I didn't even believe it from my friend until I tried it...
      Attached Files
      Last edited by Agent24; 07-15-2019, 06:16 AM.
      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
      -David VanHorn

      Comment

        #4
        Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

        Ah OK. Without schematics it will be hard to find out why CPU VCore is missing...
        Measure voltage on all the large inductors.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

          #5
          Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

          You can try getting individual ic's datasheet, if avlbl. That's the only way to proceed further if there is no visible signs of damage.

          Comment

            #6
            Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

            Originally posted by piernov View Post
            Ah OK. Without schematics it will be hard to find out why CPU VCore is missing...
            Measure voltage on all the large inductors.
            There is 19v at the drain of the high-side MOSFETs, as expected.

            There is no voltage on either inductor in the Vcore VRM as there is no gate drive to the MOSFETs.

            Presumably this is because the Vcore VRM controller, an ISL62771, is not receiving any ENABLE signal on Pin 8.
            Attached Files
            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
            -David VanHorn

            Comment

              #7
              Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

              Originally posted by mcplslg123 View Post
              You can try getting individual ic's datasheet, if avlbl. That's the only way to proceed further if there is no visible signs of damage.
              Does anyone have a datasheet or pin-out for the IT8732F? I can't find one.
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

              Comment

                #8
                Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                I mean, there's a lot of stuff going on in the power sequence to be able to reach VCore and CPU reset signal. Could be bad SIO, could be something else entirely.
                Measuring voltage on all large inductors will at least give an indication of what power rails we have on the board.

                Attached schematics apparently use the same SIO, but it's an Intel platform so will be pretty different from AMD platform.
                Attached Files
                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                Comment

                  #9
                  Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                  I already measured voltage at all large inductors, there's a 5v, a 3.3v, a 1.8v, a 1.5v, a 1.2v (actually from a linear AP1122 regulator), and a 1v rail. (see photo)

                  Every one is always present as soon as you plug in the power supply, which I guess makes sense since the thing is designed to be able to receive an HDMI signal and run the LCD and speakers while in "standby".

                  +12v for the HDD and ODD is switched on along with the power button.

                  Only Vcore never comes on at all, in either state.


                  I know what you mean about the power sequencing, but of course without correct schematic I can't check the inputs to the SIO etc.

                  Thanks for the schematic, I'll try to see if I can get anything from it, but yes, for Intel they probably have different status signals...
                  Attached Files
                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                  -David VanHorn

                  Comment

                    #10
                    Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                    Fixed! Much easier to think when it's not 3am...

                    I tried tracing the ISL62771 ENABLE line back to the SuperIO IT8732F and found it goes through two transistors, an N-Ch FET 2N7002 (Q88) and an NPN BJT, MMBT3904 (Q89)

                    When the power button was pressed, Q89 had 0.9v at its base but it was not turning on, thus it would not pull the gate of Q88 low.

                    This meant Q88 was always on, and never allowing the ISL62771 ENABLE (Pin 8) to be pulled high by its 4k7 pull-up resistor, R851.

                    I replaced Q89 with a BC846 (another general purpose NPN in SOT-23) and it works.
                    Vcore is back and the system passes POST and loads Windows just fine. Clock is wrong obviously as I had pulled the RTC battery to check it.

                    Thanks everyone for the help!
                    Attached Files
                    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                    -David VanHorn

                    Comment

                      #11
                      Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                      Nice job bro

                      Comment

                        #12
                        Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                        Originally posted by mcplslg123 View Post
                        Nice job bro
                        Thanks!

                        Originally posted by karimreza2
                        Hi
                        i cannat find the line of webcam hp probook 2560p in motherboard

                        please help me
                        Not sure what you mean (I assume you want schematics?), but you will get better help if you start your own thread about this.
                        "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                        -David VanHorn

                        Comment

                          #13
                          Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                          Nice one, thanks for the report. I'd have thought it was an issue upstream in the power sequence, but I was (thankfully) wrong.
                          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                          Comment

                            #14
                            Re: Acer Aspire Z3-105 AIO PC - no display, no POST, no VCore, won't turn off.

                            Originally posted by piernov View Post
                            Nice one, thanks for the report. I'd have thought it was an issue upstream in the power sequence, but I was (thankfully) wrong.
                            Thanks, yeah I'm glad it turned out easy too.

                            Out of interest, what kind of fault were you perhaps expecting?
                            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                            -David VanHorn

                            Comment

                            Previous template Next
                            Working...
                            X